Motor-control system



L. mi

June 15 1926.

M. F. JONES MOTOR CONTROL SYSTEM Filed April 27, 1922 INVENTOR Maa/ga FLE/les.

ATroRNEY Patented June l5, 1926.

UNITED STATES PATENT OFFICE.

MAURCE F. JONES, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

MOTOR-CONTROL SYSTEM.

Application filed April 27, 1922. Serial No. 556,823.

My invention relates to motor-control systems and it has particular relation to control systems for governing one or more singlephase corinnutator motors during regeneration.

One object of my invention is to provide a system of regeneration for a single-phase alternating-current motor, whereby the regenerative current therefrom has a relatively high power-factor and thus does not materially reduce the power factor of the current traversing the main source of supply, such for example7 as an overhead trolley systen'i-at the same time securing' a relatively great braking torque by the motor.

Another object of my invention is to secure substantially constant torque at all operative speeds for one or more alternatingcurrent single-phase eommutator motors during regeneration,

i-inother object of my invention is to provide a control system which is so designed that the operator may vary the power regenerated by the motor in accordance with the operating condition to Which the motor is subjected during regeneration.

fitill another object of my invention is to provide a control system for a singlephase cominutator motor that shall be simple and economical of construction and positive and reliable in operation.v both during motoring and regenerative periods.

inother object of my invention is to proe a control system that employs the fieldn'iagnet windings of one or more motors to serve as reactance devices in series relation with the armature of another single-phase commutator motor during the regenerative period andy at the same time. perform their normal function of exciting the field-niegue Winding of the first-named motors.

Briefly speaking, my invention comprises inserting a reactance device in series relation with the armature of a single-phase commutator motor and employing some energyvarying device in circuit with the field-mag net Winding 0f the same motor to cause the current traversing the Winding, and hence the flux thereof, to lag behind the singlephase voltage of the source of supply by more than ninety electrical degrees, preferably about 120.

My invention also comprises connecting one or more field-magnet windings of a group of motors in series relation with the v' armature of a single-phase commutator motor, and connecting the armatures of the same group of motors in series relation with one or more reactance devices during the period of regeneration to secure a high power-factor of the current regenerated thereby.

For a better understanding of my invention, reference may be made to the accompanying drawing- Figure 1 of which is a motor-control system constructed in accordance With my invention;

Figs. 2 and 3 are vector diagrams of the phase relations of the electromotive forces acting upon the motor that is illustrated in Fig. l of the drawing. during regeneration;

Fig. 4 is a diagrammatic view of a plurality of motors that are governed by a modified form of control system constructed in accordance With my invention; and

Fig. is a vector diagram of the electromotive forces acting upon the motors of the control system that is illustrated in F 4 of the drawing.

Referring to Fig. 1 of the drawing7 a motor 1, having a main or torque field-magnet finding 2 and a compensating field-magnet Winding 3 is normally ener;Y Zed, j; motoring7 by energy supplied from a suitable transformer, only the secondary Winding 4r. of which has been illustrated. The cnergization of the main field-magnet Winding 2 of the motor l is governed by a phase converter 5 having a rotor G, a primary Winding 7 and a secondary Winding 8. in adjustable inductive reactance device f) is connected in series relation with thearniature 10 of the motor 1 One terminal of the reactance device f) is adjustably connected, Y by means of a l lari] vwill equal the constant FXXsiii g5.

varying the energiuation ot the vvinrlingg T of the phase converter. @ne terminal ot t" e armature 10 ol' the inotorl inay be adjustablyY c-nnectecl to the secondary Winding #it of the niain transformer by n'ieans ot switching` Clevice 15.`

Beierence may be inaclenow to the vector diagram of Fig. 2, for the purpose ot cisplaining how the torque et the inotor 1 is maintained substantiall)1 constant during regeiwration itt the connections of the n'iotor to thesecondery Winding i of the niain trans Ytoriner are unchanged. 1t the phase-con verter 5 is rendered inoperative by the cleenergization ot the priniary winding T, and the inain ielclunagnet Winding' 2 et the niotor 1 is connected directly across that portion ot the secondary ivincling@` el ol' the niain transformer that is bet 'een the switchingil devices 1?) and 11i,Y then the voltage across the vrinding; 2 will be considered, for the purpose oit illustration7 is being equal to the vector Mot?. he current trave :sing the winding 2 ivill be at right angles to this voltaire and represented b v the vector marlrecl irlz'. the ohrnic and iron losses ot the inotor being;` oinitterl. rthe n'iagnetic 'flux ot the renin lielrlunagnet ivincling;l 2 will be, ot course. in phase with the current trarowingl the winding; and is also represented bv the saine vector. The countcrwoltage or the arniature'lO `will be in phase With the magnetic flux l? ot the iii-.iin Field-magnet Winding 2 of' the inotor 1 und is illustrated by the vector Ace.

The resultan v ot the armature voltage een :nid the voltage across that portion ot the inain transformer secondary viviiulinu t between .the ewitc ing); devices i1 aurl which has? been illustrated by the vector Tel vvill be at right angles to the current )mi trfive f the. armature 1G oit the inotor 'l vvnen. e reactance device 9,1iavingn reactance value )L iS connected in series relation with the :armature- 10. The angle qi between the cui rent ti-:aversingthe miniature l0 and the veltoi' the secondary winding; l of the niain transformer repreeentsthe phaeerelation et the regeneraplve current- -t-o the line voltage. Since the voltage M222 oit thel i'ielrl-inagrnet whirling` 2 is presuinerl to be constnntfthe nrwnetic fluir F thereof is constant.

voltage across the primary rlhe c tonne. T ot the motor 1 cliuing; regeneration ieeeee current Av1 traversing the armature 10 of the motor 1 equals #T1212 +Aco2 l -V Where X. is the reactance ot the reactancu (levice 9, the impedance ot the erinature 1() be ing neglected.

t1 9b WIT'UP +1516# Substituting thesev velues for i/-z' and sin i5 of the equation Tl-.tconstzint FHM' sin (l),

we have ./vrnfiiii 'rn T Const. le1 l' I l which equals Since the 'linx l? is directly proportional to the voltage Mo@ oil the man1 iLielrl-niegnet Winding 2, then the torque proportional to Tzenn-QLX ln other words, with a given constant excitation and terminal voltages applied to a singlephase conniutator inotor Lluring regeneration, the torque is constant and the regenerative power proportional to the speed, if the value oiE the reactance 2i con-v Vrut. The torque ot the motor 1 will vary dir etly ae the value oit terminal pressure Vl` v1 andL inversely in proportion to the value et the reactance X.

rlie choke coil or inductive reectancc rile v ce 9, in series relation with the armature x) ot the inotor 1. also prevents the current i ersii'ifr the armature fron". liecoininq' ei:- essive (hiring current surgi Any rleeirefl raking speeil nay be secured changingv the Switching connections ot of phase with the voltage oi the semni'larj,r winding 1- ot the niain transioriner. The

Wincli 'l' of the phaseconverter 5 is in phase Y'with the main transformer voltage l. The oir-citation of the winding; 7 inducesV a voltage 13o in the winding 8 that4 is 900 behind the voltage et the transformer Winding Il.

p A a letrveeuthesivitchingvlevices 13 14, ofthe -secoiirlaryvining el' ofthe main transformer to which the secondary winding 8 of the phase-converter 5 is connected, is illustrated by the vector rlll/u2. The resulting voltage across the main field winding 2 of the motor l is the vect-or sum of the voltages T212 and Pr and is represented by the vector Mv. The current MI traversing the winding 2 will be substantially 900 out of phase with this voltage or approximately l2()C behind the voltage of the secondary winding 4 of the main transformer.

The counter-voltage generated by the armature l() of the motor l will lag slightly behind the current of the main field-magnet winding 2 because of the excitation losses, and is represented by the vector Act'. The current induced in the armature l lags slightly behind the voltage Acc. The voltage of the reactance device 9 will be 90O out of phase with the current traversing the armature 10 and will be substantially equal to the voltage across the terminals of the armature 10. The voltage of the reactanee device 9 is represented by the vector Xu. The resultant of the counter-voltage Acc of the armature l0 and the voltage Xo across the reactance device 9 represented by a force which is equal and opposite to the vector Tol and is, therefore, in. phase with it.

The torque of the motor l is proportional to the product of the torque tield flux, the current AI and the cosine of the angle between the vectors representingr the flux and current. For any given set of coni'iections, the current AI increases with speed, the flux is constant and the cosine of the angle between the current and flux vectors decreases with the speed. The torque of the motor l. is, therefore, substantially constant with a considerable change in speed.

Referring now to Fig. 4 of the drawing, a plurality of motors 2l to 24, inclusive, are provided with corresponding main fieldmagnet windings to 28, inclusive, couipensating field-magnet windings 29 to 32, inclusive, and armature 33 to 36, inclusive. The adjustable reactance device 9 is connected in series relation with the armatures 34 to 36, inclusive, and compensating fieldmagnet windings 30 to inclusive, ot the corresponding motors 32 to 34, inclusive. The armature 33 of the motor 21 is con nected in series relation with the main fieldmagnet windings 26 to 28, inclusive, of the corresponding motors 22 to 24, inclusive, and a reactance device 39.

The main field-magnet winding 25 of the motor 2l is adjustably connected, by means of switching devices 4l and 42, to the secondary winding 4 of the main transformer. The armature 33of the motor 21, reactance device 39, and main field-magnet windings 26 to 28,`inclusive, of the corresponding motors 22 to 24, inclusive, are connected, by means of ,adjustable taps 42 and 43, to the secondary winding 4 of the main transformer. The armatures 34 to 36, inclusive, of the corresponding motors 22 to 24, inclusive, and the reactance device 9 are adjust;- ably connected to the secondary winding 4 of the main transformer by means of the switching device 44.

Referring to Fig. 5, the voltage between the taps 44 and 43 of the transformer winding is represented by the symbol T3, between the taps 43 and 42 by the symbol T4, between the taps 42 and by the symbol T5. The voltage across the main held-magnet winding 25 of the motor 2l is represented by the vector T5. The current traversing the main field-magnet winding is substantially 9()O out of phase with the voltage of the transformer 4, and is represented by the vector M212'. The regenerative voltage across the armature 33 of the motor 2l is represented by the vector A2101). This voltage A210@ establishes a current that traverses the windings 26 to 23, inclusive, of the motors 22 to 24, inclusive, and is represented by the vector A211. The reactive drop across the armature 33, ield windings 29, 26, 27 and 23 and reactance device 39 is represented by vector Redo, which together with vector A2102) constitute the components of the voltage vector T4.

The induced voltage across the armatures 34 to 36, inclusive, of the motors to 24, inclusive, is represented by he vector Arce. The motor 21, therefore, regenerates with a substantially constant-torque characteristic in much the same manner as the motor l in Fig. 1, when the phase-converter is inoperative, as heretofore described. The current traversing the armatures 34 to 36, inclusive, is represented by the vector Ari and lags behind the voltage impressed upon the armatures 34 to 36, inclusive, because of the react-ances of the compensating windings 34 to 36, inclusive, and of the reactance device 9. rllhe reactance device 9 and the compensating field-magnet windings 30 to 32, inclusive, of the motors 22 to 24, inclusive, have a reactance voltage XW thati is equal to the voltage impressed across the terminals ot the armatures 34 to 36, inclusive, of the motors 22 to 24, inclusive, and is substantial- .ly at right angles to the current traversing these armatures. The resultant of the voltage Arce, which is generated by the armatures 34 to 36, inclusive, of the corresponding motors 22 to 24, inclusive, and of the reactance voltage Xxrfv of the reactance device 9 and the compensating field-magnet windings 30 to 32, inclusive, is in phase with. the voltage of the secondary winding 4 of the main transformer, being opposite in direction.

The braking etii'ort of the motors 2l to 24, inclusive, may be increased by increasing the 'excitation et the ina-in field-magnet winding 25 ot' the motor 2l or by shit-ting the taps that connect the armatures 34 to 36, inclusive, ot the motors 22 to 24, inclusive, to the secondary winding 1lof the main transformer. The braking effort ot' the motors may be varied by changing the reactance values ot' the reactance devices 9 and 39. As explained above, the braking etlort ot the motor 2l substantially constant, regardless ot speer". lith the motors 22 to 2li, inclusive, the torque iield linx increases with speed, the cui lcnt Afri; decreases with speed 'for a certain range and then increases, While the cosine ot' the angle between the lux and the current first increases and then decreases. The combined braking effort oit the motors 2l to 2d, inclusive, is substantially constant over the operating range of speed ot the motors.

From the above description, it is apparent that l have provided system or control for governing the operation ot one or more single-phase commutator motors during regeneration to improve the power tactor ot the circuit, and that the torque ot the motors may be inherently maintained constant; or, it desired, may be varied by the operator varying the connections ot' the motors to the source ot supply.

wWhile I have shoivn my invention in its preferred `it'orm, it is apparent that minor modifications may be made in the manner of securing the lag of the field-magnet Winding current over electrical degrees behind the voltage ot the source ot' energy, Without departing 'from the spirit oic my invention. desire, therefore, to be limited only by the scope ot the appended claims.

l claim as my invention l. ln a motor-control system, the combination with a source ot energy and a singlephase connnutator motor having an armature and a Vtield-n'iagnet Winding, of a circuit tor energizing said Winding from said source, and a rcactance device independent ot said circuit and in series relation with said armature to maintain the torque ot said motor substantially constant during regeneration.

2. ln a motor-control system, the combination with a source ot' energy and a singlephase commutator motor having an arma-- ture and a field-magnet Winding, ot a circuit tor energizing v said Winding Jfrom said source, a rcactance device independent ot said circuit and in series relation with said armature, and means tor varying the energization ot said nf'indin'g during regeneration.

3. ln a motor-control system, the combination ivith a single-phase coinrnutator motor having an armature and a lield-mafgnet Winding. oi a reactance device in series relation with said armature and means comprispliasel-distorsing device-tor' varying Lacasse the energization of said Winding to improve the povver tactor ot the current regenerated by said motor. l

el. ln a inotor-control system, the combination with a single-phase commutator inotor having an armature and a held-magnet Winding, ot' a reactance device in series relation Wit-li said armature and means comprising a phase-converter for varying the iiui; of said Winding to improve the power-factor or' said motor during regeneration.

5. ln a motor-control system, the combination with a single-phase commutator motor having an armature and a field-magnet Winding, ot variable reactance device in series relation with said armature, and means for varying the linx of said Winding to improve the power factor of said motor during regeneration.

6. ln a motor-control system, the combination With a single-phase commutator motor having an armature and a field-magnet Winding, ot a variable reactance device in series relation with said armature to maintain constant torque, and a phase-converter in series relation with said Winding during regeneration.

7. ln a motor-control system, the combination with a single-phase commutator motor having an armature and a Held-magnet Winding, of a transformer having a plurality oi taps 'tor energizing said motor during motoring, a variable reactance device in series relation with said armature to maintain the torque of said motor substantially constant during regeneration, a phase-converter 'tor varying the flux ot said winding, and means tor varying the connections oi said armature and said phase-converter to said transformer.

8. ln a motor-control system, the combination with an alternating-current dynamoelectric machine having an armature, a torque field-magnet Winding and a coinpensating tield magnet Winding, ot a source ot electrical energy, a reactance device connected in series, with the mot-or arma.- ture and compensating eld Winding and across said power source, said reactance device being adapted to maintain the torque ot the motor substantially constant during regeneration, a phase converter provided with primary and secondary windings, said secondary Winding being connected in series with the motor torque field Winding and to the power source to control the 'thin in the torque field Winding.

9. ln a motor-control system, the combination with an alternating-cinrent dynamoelectric machine having an armature, a torque iield magnet. Winding and a compensating tield magnet Winding, ot a source of electrical energy, a reactance device connected in series with the motor armature and compensating' field winding' and -acrossseid l. Gt)

power source, said reactanee device being adapted fo maintain the torque of the motor Substantially constant during regeneration, a phase converter provided with primary and secondary windings, said secondary winding being connected in series with the mot-or torque field Winding and to the power source to Control the luX in the torque field winding, and ineens for connecting the primary winding of the converter to the power source.

In testimony whereof, I have hereunto subscribed my name this 18th day of April l 0 H' MAURICE F. JONES. 

